—Do you know our city at all?  

—Yes, quite well, this is the fourth time I _____ here.  [ ]

A. had been

B. have been

C. was   

D. am

港航工程施工合同规定双方保险义务，（）的投保一般在合同专用条款中约定由甲方承担。

A.建筑工程一切险

B.勘察设计一切险

C.船机设备保险

D.施工人员保险